The invention relates to a mosaic printing head for use in producing a desired printed pattern by selective energization of one or more of a plurality of printing members.
Known prior art methods of printing with a matrix type head are disclosed in the German published specifications No. 1 039 769 of Buser and No. 1 132 158 of Preisinger. In the publication to Buser, an array of magnetostrictive elements is selectively energized in order to produce a desired printed pattern. Preisinger shows a similar construction in which exciter windings are wound around magnetostrictive rods, which rods are caused to elongate, and consequently, to print upon a recording medium due to an excitation signal impressed upon the windings. The German published application No. 24 58 809 of Stecker et al discloses a rolling motion printer in which an array of solenoids having a plunger-like action is made to selectively contact regions of a printing medium in order to produce a mark thereon. German Pat. No. 681 442 of Devaux shows a printing hammer which is actuated by a stack of piezoelectric crystals. The hammer is positioned so as to contact a printing pin to drive an inked ribbon into contact with a printing medium.
The devices of the prior art suffer from the disadvantage of a very small amount of mechanical power being developed by the printing members at the most extended position of a printing stroke. Also, the rapidity of the printing strokes is often too slow, and any bounce or chatter of the member on return to the rest position further slows overall operation.